North Korean threat: How would the United States react to a nuclear attack?

FILE - In this Sunday, April 15, 2012 file photo, a North Korean vehicle carrying what appears to be a new missile passes by during a mass military parade in Pyongyang's Kim Il Sung Square to celebrate the centenary of the birth of the late North Korean founder Kim Il Sung. North Korea has moved a missile with "considerable range" to its east coast, South Korean Defense Minister Kim Kwan-jin said Thursday, April 4, 2013 but he added that there are no signs that Pyongyang is preparing for a full-scale conflict. The report came hours after North Korea's military warned that it has been authorized to attack the U.S. using "smaller, lighter and diversified" nuclear weapons. It was the North's latest war cry against America in recent weeks, with the added suggestion that it had improved its nuclear technology. (AP Photo/Ng Han Guan, File)